The present invention relates to an anode and a battery using it, particularly to an anode effective in the case that the anode has an anode active material layer which is capable of inserting and extracting an electrode reactant and contains a metal element or a metalloid element as an element, and a battery using it.
As electronic technology has been advanced in recent years, portable electronic devices such as a combination camera, a mobile phone, and a laptop personal computer have been developed. Accordingly, as a power source for such electronic devices, development of small and light secondary batteries having a high energy density has been strongly demanded.
As a secondary battery meeting such a demand, a secondary battery using a light metal such as lithium (Li), sodium (Na), and aluminum (Al) as an anode active material is promising. According to such a secondary battery, a high voltage can be theoretically generated, and a high energy density can be obtained. Specially, since the secondary battery using a lithium metal as an anode active material can provide a higher output and a higher energy density, research and development thereof has been actively implemented.
However, when a light metal such as a lithium metal is used as an anode active material as it is, dendrite crystal of the light metal is easily precipitated on the anode in the process of charge and discharge. When the dendrite crystal is precipitated, the current density of the end thereof becomes very high, and therefore an electrolytic solution is easily decomposed and cycle characteristics are lowered. Further, when the dendrite crystal reaches the cathode, internal short circuit occurs.
Therefore, in order to prevent such precipitation of dendrite crystal, a secondary battery, not using a lithium metal as an anode active material as it is, but using an anode material capable of inserting and extracting lithium ions has been developed.
As such an anode material, carbon materials have been widely used traditionally. In recent years, in order to obtain a higher capacity, using silicon (Si), tin (Sn), or an alloy thereof has been considered (for example, refer to Japanese Unexamined Patent Application Publication No. 2000-311681).
However, there has been a disadvantage that in the anode material using silicon, or tin as above, cycle characteristics are lower than in the carbon materials, and it is difficult to take advantage of the feature, the high capacity.